Microsoft was one of the first companies who fully internalized the importance of seamless backwards compatibility. The lessons had been around for a while, such as the fate of the 1200XL.

They would have done a lot better, even at a higher price, if they had focused on it. The Atari 8-bit line had a lot going for it and was arguably superior (flame wars incoming, Atari army please help me) in many ways than the C64.